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Tornadoes could be the next best thing in wind energy say researchers who are developing a machine that makes artificial ones and harnesses their power.

The atmospheric vortex engine, an invention by Canadian petroleum engineer Louis Michaud, could also be used to capture waste heat from power plants and convert it into useable megawatts.

"Two hundred megawatts would supply the electricity needs of a city of 100,000 people with 25,000 homes," says Michaud, whose theories were tested earlier this year in Utah at an experimental tower owned and operated by colleague and computer engineer Tom Fletcher.

The vortex engine is based on atmospheric convection, what happens when the Sun heats the ground and hot, moist air rises and expands.

In the process of cooling and condensing into rain, it releases energy, then sinks back to Earth, where the Sun warms it once again.

In nature, this cycle of rising and sinking air can produce tornadoes and hurricanes.

Michaud realised if he could tap into the strong updraft created under these conditions, he could potentially generate emission-free electricity.

He began to study meteorology and published nine articles in peer-reviewed journals that described his theories.

Prototype engine

The vortex engine prototype in Utah is a round tower that stands 15 metres tall and 30 metres in diameter.

Fuel spread in a circle on the floor of the tower is burned to generate heat. A series of air inlets around the tower's perimeter feed hot, humid air into the interior at an angle that promotes the whirling motion of a tornado.

In initial tests, Michaud and Fletcher produced vortices more than a metre across.

A full-sized atmospheric vortex engine would be a lot bigger, about 100 metres high with a diameter of 400 metres.

Its artificial tornadoes would measure 50 metres at the base and extend through the roofless tower to 20 kilometres.

The vortex can be controlled by increasing or decreasing the hot air coming in through the inlets around the base.

And although no turbines have been installed yet in the prototype, they would eventually be positioned around the base to capture the energy created by the updraft and convert it into electricity.

Used with a power plant

Michaud believes that a vortex engine could do its best work when used with a power plant.

Such plants, whether coal, nuclear, or gas, already rely on cooling towers to condense steam, which is used to turn the turbines that generate electricity.

Because cooling towers cost more than a US$100 million (A$136 million) and need to be rebuilt about every 20 years, Michaud envisions replacing them with a vortex engine.

He says the engine could convert the heat into electricity, instead of wasting it, and improve a power plant's efficiency by 20%.

"It's a brave sort of idea," says planetary scientist Dr Ralph Lorenz, an assistant research scientist at the University of Arizona in Tucson.

"The thing that is exciting about it is that even if it's not competitive with solar panels as a power source in the industrialised West, because it doesn't involve an awful lot of high-tech components, it could be easily applied to third world economies."

But Michaud would like to garner the interest of power companies, and although he's had a few calls, no one has made a serious offer.

He is moving forward with his tests and will be presenting his latest results at the American Geophysical Union's meeting in December.